CO2-enriched, low, and very low, vapor pressure liquid hydrocarbon fuels

ABSTRACT

This invention is a mixture of low-vapor-pressure hydrocarbon fuels and carbon dioxide mixed at normal pressures and temperatures in a ratio that facilitates the production of micro-droplets that enhance combustion in diesel and similar fuel burning engines resulting in a reduction of particulates ejected and a gain in efficiency. The presence of the gas in the fuel also decreases flammability in the atmosphere above the fuel surface.

TECHNICAL FIELD

[0001] This invention pertains generally to the physical compositionformed by the combination of carbon dioxide (CO2) absorbed in liquidhydrocarbon fuels having low, and very low vapor pressures. Theinvention includes fuels used in fuel-powered engines and devices, suchas: diesel and jet aircraft engines, fuel-oil burning devices such asdomestic and commercial heating systems, or electrical power generationfacilities, and resid-oil burning engines such as those used in largecargo ships.

BACKGROUND OF THE INVENTION

[0002] More particularly, the present invention is a CO2-enriched, low,or very low, vapor pressure hydrocarbon fuel having objectives andadvantages that are important to the fuel industry, to the environment,and to fuel economics. The present invention:

[0003] a.) provides improved combustion characteristics;

[0004] b.) promotes fuel micro-droplet production;

[0005] c.) reduces exhaust soot particulate;

[0006] d.) reduces exhaust carcinogens;

[0007] e.) may be effective in reducing the infrared ‘footprint’ of theexhaust of military aircraft and vehicles;

[0008] f.) de-oxygenates fuel (including at NTP) during the CO2/fuelmixing process;

[0009] g.) provides a means to reduce the complexity and cost of fueltank inerting systems;

[0010] h.) provides a cost-effective interim emissions-reducingtechnology for existing engines that can readily be implemented,particularly in cities having high atmospheric soot particulate;

[0011] i.) provides potential tax credit relief to fuel companies foraccelerated ground-based vehicle and aircraft soot particulatereductions;

[0012] j.) provides a means to reduce fuel viscosity (when desired);

[0013] k.) may be effective in cleaning fuel-injection systems;

[0014] l.) may be effective in improving fuel economy;

[0015] m.) which, through improved fuel economy may provide a netreduction in CO2 production (CO2 in exhaust/per gallon);

[0016] n.) which, through improved fuel economy may provide acost-savings in fuel-use which is near, equal to, or greater than, thecombined cost of CO2, CO2-enriched fuel/technology licensing, andsystems/equipment used for fuel tank ullage inerting;

[0017] o.) which can utilize an industrial CO2 that is recovered(re-cycled) from industrial stacks and vents

[0018] p.) provides new enhanced fuel transferring and storing safety;

[0019] q.) acts as a ‘self-inerting fuel’;

[0020] r.) uses fuel as a ‘weightless container’ for transferring andstoring substantial volumes of CO2;

[0021] s.) provides a new means for safely extending Jet-A fuel suppliesby mixing in percentages of JP-4 or naphthas into CO2-enriched Jet-A(e.g. during fuel shortages, fuel embargoes, or in times of nationalsecurity if Jet-A supply needs to be increased, for example, during war,or other international crisis).

[0022] t.) provides a sufficient volume of CO2 in fuel (including atNTP) such that the CO2 will serve as an inerting medium in the ullagesof fuel tanks to which such fuel is transferred and stored, or wheresuch gas is extracted from fuel derived from such tanks and isimmediately, or is stored and subsequently, directed back into that fueltank's ullage;

[0023] u.) is transferrable and storable in, existing fuel distributionsystems/equipment such as those used at airports and other re-fuelingterminals;

DESCRIPTION OF THE RELEVANT ART

[0024] Reference: Jones, Minor C, K, 2,303,950 Ginsbrugh et al, 6,293,525 B1

[0025] Search of prior art has not revealed any patents having thecombination of the CO2 and liquid hydrocarbon fuels as specified in thepresent invention, or having a type of gas-fuel that would betransferable or storable in existing fuel distribution infrastructures;fuel delivery systems, vehicles and equipment, or in standard fuel tanksfound in diesel trucks, aircraft, ground-based vehicles, and ocean-goingvessels or; the tanks used for supplying heating devices or atpower-generation facilities. The search also did not reveal theabove-mentioned actual and potential benefits of the present invention,such as an ullage-combustion suppressive ‘self-inerting fuel’; a meansto improve combustion and/or fuel economy; a means to promote reducedfuel-droplet size (sometimes referred to as fuel “micro-droplets”); or ameans, through reduced fuel-droplet size, to reduce soot particulateemissions and carcinogens in the exhaust of liquid hydrocarbonfuel-powered engines or devices, because the smaller droplets more oftenburn to extinction quicker. For reference purposes, the search did findJones, which teaches the mixing of carbon dioxide in an aviationgasoline (a positive vapor pressure hydrocarbon fuel with added volatilefuel ends) where Jones processes the fuel and/or maintaines it withadditional physical apparatus in an unconventional manner. For example,the aviation gasoline of the Jone's patent must first go throughphysical apparatus comprising a vacuum-inducing means. This apparatus isrequired to produce and sustain a negative atmospheric condition in abaffled vertical fuel mixing tank (a vacuum-maintaining tank) in orderto first promote the removal of absorbed oxygen from Jones' aviationgasoline. Immediately following the oxygen removal stage, CO2 is addedto replace it. It should also be noted that the Jones' patent seeksseveral results that, due to fuel chemistry changes in years followingthe expiration of the patent, are no longer needed in, or attainablewith, contemporary commercial grades of fuel. Furthermore, puttingpositive vapor pressure fuel in a vacuum state will pull out lighterends (such as butane) from the fuel, which will adversely affect fuelperformance. Continued exposure to a vacuum will remove the middle rangeof hydrocarbon molecules and ultimately the heavier range of molecules.The Jones patent intent was a vacuum removal of one gas and providepositive pressure (greater than 1 atmosphere) for placement andmaintenance of another gas (CO2), a means to remove oxygen from fuelthat might otherwise degas into the vapor space (ullages) of aircraftfuel tanks containing the Jones'-processed aviation gasoline. Bycontrast, the composition of the present invention can be achieved withgas-fuel mixing at NTP (normal temperature and pressure) i.e. withoutnegative and positive pressure mixing stages and uses the CO2 as aninerting medium. It is also noted that contemporary aviation gasolinenow contain anti-oxidants that are inexpensive and do not require thefuel vacuum and pressurization stages needed to process the Jones' fuel.Whereas this invention is based upon hydrocarbon fuel havingcontemporary needs which it satisfies. CO2 solubility in contemporarygrades of hydrocarbon fuels, show that CO2 concentrations in the rangeJones specifies would require constant positive-pressure (if nothi-pressure) storage and handling conditions. Thus, the only way tomaintain Jones' 100%-300% concentrations of CO2 in modern aviationgasoline would be to make, transfer, distribute, and store, the fuelcontinuously under impractical (or as Jones says “super atmospheric”)pressures. It is widely known that virtually all fuel tanks of dieseltrucks, aircraft and other ground-based vehicles, are vented to allowfor expansions and contractions of fuel-tank ullages caused by altitudeand temperature changes, and by fuel usage. Thus, it would be necessaryto retrofit all such vehicles with unvented pressure-capable tanks inorder to store aviation gasoline having the Jones' concentrations of CO2(up to and including the “five atmospheres” he specifies). This goalwould be especially challenging in that a commercial aircraft willtypically experience a change of four atmospheres in the various phasesof a single flight (which is why their tanks must be vented). It wouldalso be necessary to have specially equipped fuel transportationvehicles for the delivery of Jones' pressurized gasoline. Suchprerequisites to the processing, transferring, transportation, handling,and use of Jones' aviation gasoline again, are evidence that Jones didnot achieve a practical physical composition patent, especially as itpertains to contemporary technology. Rather, the Jones' physicalcomposition can only exist with the employment of unconventionalphysical apparatus that in the contemporary fuel market are not onlyunnecessary, they would require a costly re-building of entire fueldistribution and storing systems. By contrast, the present inventionprovides gas-fuel mixtures with fuels other than gasoline (hydrocarbonfuels with low, and very low, vapor pressures at NTP), where suchmixtures are attainable and/or storable at NTP having effectiveconcentrations of CO2 that provide new fuel safety-enhancing andimproved combustion advantages. These advantages are achieved withoutJones' hi-pressure transportation, handling and storage conditions.Lastly, the Jones patent decribes a safety-enhancing aspect of his fuel,which, assuming the gas concentrations he specifies were attainable, isintended to reduce the danger of fuel fires in the event of catastrophicfuel tank ruptures. For example, the Jones' fuel is described as beingadvantageous during aircraft crashes, or during fuel tank rupturescaused by bullets piercing the tanks in times of war. In contrast, thepracticably attained physical composition of the present invention iscomprised of CO2-enrichment of low, or very low, vapor pressure fuels,whose safety-enhancing characteristics are only intended to inert thecontents of the ullages of fuel tanks that are intact (i.e.non-ruptured).

SUMMARY OF THE INVENTION

[0026] Vehicles and devices that burn low, and very low, vapor pressurehydrocarbon fuels have been in use for over a century and the chemistrycomposition of such fuels (including relatively newer jet fuels) havelargely remained the same since their commercialization. While suchfuels offer a potent source of power to the respective engines ordevices that utilize them, they also have drawbacks that the physicalcomposition of the present invention can help to reduce. For instance,it has recently been declared by the California State Air Quality Boardthat the black soot emissions that emanate from a diesel engine (used incars, trucks, heavy equipment, trains, ships and the like), and the sootfrom jet turbines, are carcinogenic. Thus, practicably attainable fueltechnology, which improves diesel and jet fuel combustion, particularlyduring its acceleration phase (highest emission emitting phase), andotherwise reduces such emissions, provides an important and timelysolution to this environmental and health-related concern. Recent testsconducted with California State-Approved Infrared Test Equipmentconcluded that the improved fuel of the present invention reducesharmful emissions by as much as 60% during repeatable accelerations onan unmodified diesel engine when using an optimum and/or controllableconcentration of CO2 absorbed within Diesel #2 fuel. Further testingusing a standardized EPA test produced similar reductions in soot.

[0027] Alternatively, by controlling concentrations of CO2 absorbedwithin low vapor pressure hydrocarbon fuels, the physical composition ofthe present invention is also effective in enhancing the safety of thefuel when it is stored in storage receptacles, whether such receptaclesare stationary or reside in any one or more of a variety of liquidhydrocarbon fuel-powered vehicles. For instance, hydrocarbon-based fuelscan evaporate fuel into a vapor space, or ullage, of the fuel receptaclein which they reside. These evaporated vapors are usually low molecularweight hydrocarbons which mix with the air in the ullage, and undercertain conditions have proven to be dangerously explosive. Even JP-4 (amilitary aircraft fuel which is mostly kerosene with some low molecularweight naphtha) usually has a flammable ullage above the fuel and thisvolatile chemical condition has had deadly consequences. FAA expertshave concluded that the mid-air explosion of TWA FLT 800 out of New Yorkwas due to flammable vapors which were emitted from relatively heatedJet-A fuel located in the plane's center fuel tank.

[0028] Enhanced safety in the storing and/or transporting of these fuelscan be achieved by reducing the amount of air which can enter, orotherwise reside above the fuel of such fuel tanks by displacing orreplacing the air with an inert gas concentration that will no longersupport combustion. For example, approximately 40% or greaterconcentration of CO2 will effectively suppress fuelullage-combustibility under most operating conditions. The CO2-enrichedhydrocarbon fuels of the present invention provide this desirablecombustion-suppressive condition in two ways. In the first method, theconcentration of inert-gas residing in a particular fuel exceeds thatfuel's equilibrium CO2/fuel state and consequently degasses excess CO2from the fuel under known conditions, such as: the passage of time,increases in temperature, agitation of the fuel, and/or a change inrelative pressure—such as the ascent of a commercial aircraft to acruising altitude. In this first method, CO2-enriched fuel can betransferred to a fuel tank such that a known excess concentration of CO2degasses from the fuel during re-fueling; for example when the fuel tankis only being partially filled with fuel (and the excess degassed CO2serves to inert the ullage above the fuel level). In the second method,CO2-enriched fuel is pumped from the fuel tank and a gas-scavengingstage of the pump extracts CO2 from the fuel and the extracted CO2 iseither directed back into the same fuel tank (e.g. its ullage), or isstored in one or more CO2 storage receptacles for subsequent fuel tankinerting purposes (as described in co-pending patents). In either case,the intended equilibrium state can deliberately be exceeded (without thevacuum stage described in the Jones patent). For example, CO2 can bemixed in the fuel under controllable positive pressures or under suchpressures with agitation (as described in co-pending patents), in whichcase the fuel is still transferable and storable in conventional fueldelivery systems, and the excess gas will subsequently degas atpredictable rates and/or volumes. For example, an aircraft having ashorter duration flight could be fueled with a CO2-enriched Jet-A fuelhaving a gas-to-liquid ratio of CO2 that is absorbed at a substantiallyhigher ratio, that is achieved by employing a higher mixing pressure ofthe CO2 in the liquid fuel, to promote faster degassing than with fuelwhich is mixed at lower, or ambient, pressures (suitable for longerflights). It is also noted, that in consideration of the environment,the quantity of CO2 necessary to inert a commercial aircraft, such as aBoeing 747 flight of 6.5 hours and a distance of 3000 nautical miles, isequal to the amount of CO2 emitted during just a few seconds of engineexhaust from the flight. Furthermore, the present invention includes themixing of a commercial grade of CO2 that has been recovered (re-cycled)from high-CO2-content industrial stacks and vents. Moreover,standardized EPA testing, exhaust pyrometer testing, and engine RPManalysis have each indicated that improved fuel performance may becaused by the CO2-enriched fuels of the present invention (the improvedfuel economy being caused by the CO2 reducing fuel droplet size, and/orby a cleaning of fuel injection components). For a frame of reference:each one half percent improvement in fuel economy would reduce the 747's3000 mile flight output of CO2 by 2200 pounds (this is several times theamount of CO2 needed to inert the fuel tanks during the entire flight,and thus, would represent a net reduction in CO2 production).

[0029] Thus practicably attained CO2-enriched liquid hydrocarbon fuelsare provided which overcome significant shortcomings of gas-fuelmixtures requiring special processing, handling, and unconventionalphysical apparatus, and which achieve an enhanced safety fuel, as wellas an improved combustion fuel, and do so using inexpensive (andoptionally recycled) CO2.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030]FIG. 1 shows a graph of the volume of “Carbon Dioxide” (CO2) thatcan be mixed, or absorbed, in a volume of low vapor pressure liquidhydrocarbon fuels, namely “JP-4/Jet-B”, “JP-8/Jet-A”, “JP-7”, and“JP-5”.

[0031]FIG. 2 is a diagrammatical depiction of a barrel of crude oilillustrating the hydrocarbon fuel constituents of the barrel, and rangesof fuel in the barrel representing “Low, and Very Low, Vapor PressureFuels”, “High Vapor Pressure Fuels”, “Jet-A1 or JP-8”, “JP-3”, “JP-4”,and “JP-5”.

DETAILED DESCRIPTION OF THE INVENTION

[0032] The graph in FIG. 1 plots volume ratio and depicts a range of thevolume of CO2 that can be mixed, or absorbed, in a volume of low vaporpressure liquid hydrocarbon fuels, namely “Diesel, JP-4/Jet-B”,“JP-8/Jet-A”, “JP-7”, and “JP-5 and shows that as temperature goes upthe volume ratio of the CO2 within the fuels goes down. For example, at−20° C. about 1.7 volumes of CO2 can be absorbed in one volume ofJP1-Jet-A. At just under 50° C. an approximate 1:1 ratio of gas to fuelis possible. Commercial vehicle and aircraft fuels such as diesel#2 andJet-A have a similar composition and consequently similar absorptionratios of gas to fuel are possible.

[0033] Several physical factors are known to change the ratio ofinert-gas which is mixable in, and/or retainable within, a particulartype of low, or very low, vapor pressure liquid hydrocarbon fuel; theCO2 gas is physically absorbed without reacting chemically with thefuel. These factors can be controlled, or predicted, and in numerousinstances require no additional physical structure, or equipment, inorder to occur. These factors include: temperature change, pressuredifferential, agitation, time, and, convection of the mixed or mixingfuel. Thus, a factor such as a known temperature change during a mixingphase, or during a degassing phase, will have predictable results whichcan be advantageously used. For example, cooler CO2-enriched liquidhydrocarbon fuel may be stored in relatively cooler underground tanks,with the knowledge that as the fuel becomes warmer it will degas fasterat a known rate. Similarly, agitation during a mixing phase or during adegassing phase will have predictable results. For instance, afterrefueling a vehicle or aircraft will encounter fuel agitation as itrolls over the natural series of bumps such as one encounters on roads(car), or during a 40 second or so takeoff roll (commercial aircraft).Alternatively, a pressure differential can be exploited to accelerategas absorption in, and/or desorption from, fuels, as mentionedpreviously in the case of aircrafts having different flight durations.Time is also a known factor that can be used advantageously to predictabsorption or desorption rates, including rates when also affected byany of the above-mentioned factors that can change the ratio of thephysical composition. Or CO2-enriched fuel can be made with a gas/fuelratio that remains fairly stable through all phases of a flight (i.e.through all changes in altitude).

[0034] In the case of the physical composition being used as a vaporcombustion-suppression fuel, it can be beneficial to mix CO2 in fuelssuch as diesel #2 or Jet-A in a ratio that exceeds the fuel'sequilibrium state of the gas/fuel mixture (such as that exceeding the50% ratio previously mentioned). For example, a 1.5:1 gas/fuel ratiomight be employed where 0.75 of a fuel's CO2 volume is meant to degasfrom the fuel under relatively ambient conditions, and more CO2 candegas, or be extracted from the fuel, according to one or more of thefactors or methods previously mentioned. Since an ullage in a tankcontaining a typical hydrocarbon-based fuel can be inerted by containingapproximately 35% or more volume of CO2 therein, it can be seen that asufficient volume of inert-gas can be retained within the fuel to ineffect act as a “self-inerting-fuel”.

[0035] In the case of the application of these physical compositionsproviding an improved combustion and/or emission-reducing fuel, it canbe beneficial to mix the CO2 with the hydrocarbon fuel in less than 1:1to 3:1 gas/liquid ratio of CO2 to fuel (e.g. a range from 0.1:1 to 1:1)gas/fuel ratios in the approximate range of 15-25% that have been shownto reduce harmful particular emissions in diesel #2 fuel by as much as60%. The various CO2/fuel ratios may indicate that minute inert-gasbubbles can form in ‘micro-droplets’, and upon reaching the surface ofthe droplet can disperse the droplets into smaller ones which creates alarger mixing surface for fuel and air molecules for optimizeddispersion of the fuel which results in improved (and more complete)combustion in an engine or fuel-burning device. This benefit may be offurther advantage during cold weather, or during cold-engine starting.

[0036] Additionally, liquid fuel convection is a means of replacingsurface fuel molecules so that they may absorb CO2 molecules from ablanket of CO2 gas above the liquid surface. Thus, the factors ofconvection and time, or convection and fuel temperature and/or CO2temperature, or other factors mentioned above can be predictable andused advantageously to attain desired CO2/fuel concentrations andresults. Without the surface layer of CO2 the same methods createdegassing of the CO2.

[0037] Because a CO2-enriched low vapor pressure fuel can be easily andpracticably attained by a number of controllable methods, with theoutcome being a CO2/fuel mixture that is transferrable and storable inexisting fuel distribution systems, the present invention provides afuel that can be easily made at a number of junctures in the fueldistribution system. For instance, at an airport fuel farm, at any oneor more of a variety of re-fueling terminals, in underground storagetanks, on fuel tankers, fuel barges, on a ship, and the like.

[0038]FIG. 2 shows a diagrammatical depiction of a barrel of crude oilillustrating the hydrocarbon fuel constituents of the barrel. Ranges offuel in the barrel representing low vapor pressure fuels are bracketed,and those representing high vapor pressure fuels are separatelybracketed. It can also be seen in FIG. 2 that Jet-A1 or JP-8 can bederived from 10% of the crude, JP-3 from 50% of the crude, JP-4 from 25%of the crude, and JP-5 from 2% of the crude. An important benefit of thepresent invention pertains to fuel supply, particularly during anational emergency such as a fuel shortage caused by any one of a numberof factors, such as an international crisis, a war, a fuel embargo, oran international trust type of control over the supply/cost of fuels. Inany such instance, for example a shortness of supply in Jet-A fuel couldthreaten national security (since this fuel is used in militaryaircraft). Heretofore, JP-4 fuel has been eliminated from fuel supplies,due to proven fuel tank ullage volatility associated with its highervapor pressures. The range of CO2-enriched fuels of the presentinvention, and the range of CO2 that can be absorbed within low, andvery low vapor pressure fuels, make it possible to significantlyincrease jet fuel supply in times of emergency by providing the means toextend CO2-enriched Jet-A supplies by mixing in percentages of JP-4 orNaphthas (and increasing CO2 as needed), or increasing other usable jetfuel supplies by mixing suitable concentrations of CO2 in one or morenon-Jet-A “JP” fuels. Such an approach can alternatively be employed ina non-crisis situation, for instance where a government/country may beclose to being self-sufficient in one or more fuel and could attainself-sufficiency by a prudent mixing of jet fuels and CO2.

[0039] The fact that carbon particulate is reduced in the engine exhaustmeans that any infra-red emissions from this source are also minimized.This can have value to military exhaust cloaking efforts.

[0040] Although the present invention has been described with a certaindegree of particularity, it is understood that the present disclosurehas been made by way of example, and changes in detail or structure maybe made without departing from the spirit of the invention as defined inthe appended claims.

1. A composition of hydrocarbon fuel, in the low vapor pressure range tovery low vapor pressure range, and carbon dioxide (CO2) wherein theconcentration of CO2 within the fuel is sufficient in volume to achievea substantial reduction in exhaust soot particulate when the fuel isconsumed by engine combustion.
 2. A composition of hydrocarbon fuel, inthe low vapor pressure range to very low vapor pressure range, whereincommercial grade of recycled carbon dioxide CO2 is used and wherein theconcentration of CO2 within the fuel is sufficient in volume to achievea substantial reduction in exhaust soot particulate during enginecombustion.
 3. The composition of claim 1 and 2 wherein said CO2 ismixed under normal temperature and pressure within said fuel, and theCO2 does not react chemically with the fuel.
 4. The composition of claim1 and 2 wherein the combination of said fuel and said CO2 is employed toimprove fuel economy.
 5. The composition of claim 4 wherein thecombination of said fuel and said CO2 is employed to provide a netreduction in CO2 production in engine exhaust.
 6. The composition ofclaim 1 and 2 wherein the combination of said fuel and said CO2 isemployed to provide a net fuel cost savings.
 7. The composition of claim1 and 2 wherein the combination of said fuel and said CO2 is employed toreduce fuel viscosity without entering into a chemical reaction.
 8. Acomposition of: liquid hydrocarbon fuel, in the low vapor pressure tovery low vapor pressure range, and carbon dioxide CO2: wherein theconcentration of CO2 within the fuel is less than 1 atmosphere ofpressure and sufficient in volume to provide a substantial supply ofinert gas for use in fuel tank ullage inerting purposes and the CO2 doesnot react chemically with the fuel.
 9. The composition of claim 8wherein: hydrocarbon fuel is in the low vapor pressure to very low vaporpressure range, and uses a commercial grade of recycled carbon dioxideCO2 wherein the concentration of CO2 within the fuel is sufficient involume to provide a substantial supply of inert gas for use in fuel tankullage inerting purposes.
 10. The composition of claim 8 wherein thecombination of enhanced fuel by the added CO2 provides an improved fuelfire safety factor when said enhanced fuel is transferred and stored.11. The composition of claim 8 wherein the combination of said fuel andsaid CO2 acts as a self-inerting fuel.
 12. The composition of claim 8wherein the combination of said fuel with said CO2 provides that saidfuel acts as a ‘weightless container’ for transferring and storingsubstantial volumes of CO2 without additional containment vessels. 13.The composition of claim 8 wherein the combination of said fuelcontaining said CO2 wherein that concentration of CO2 in the fuel may beextracted from the fuel by mechanical means.
 14. The composition ofclaim 8 wherein the combination of said fuel and said CO2 istransferable and storable in, existing closed fuel distribution systemsand fuel delivery equipment such as those used at airports and otherre-fueling terminals.
 15. The composition of claim 8 wherein thecombination of said fuel and said CO2 provides a new means for safelyextending Jet-A fuel supplies by mixing in percentages of JP-4 ornaphtha into CO2-enriched Jet-A.
 16. The composition of claim 8 whereinthe combination of said fuel receiving said CO2 provides substantialfuel de-oxygenation during the CO2/fuel mixing process.